Mood disorders collectively represent one of the most common mental illnesses. Patients with mood disorders are more likely to have various physical illnesses compared to the general population. Of these diverse physical illnesses, poor oral health conditions are common, but they are often neglected in the care of mood disorders. This review examines the currently available evidence that altogether shows that oral disease both is common in patients with mood disorders and affects the course of mood disorders. In particular, oral disease is found to be common in patients with mood disorders, and patients with mood disorders put less effort toward oral hygiene than the general population. Symptoms of mood episodes, comorbid tobacco, alcohol, and substance use, diet, and pharmacological agents for mood disorder are all factors that could worsen oral health by worsening oral hygiene care. Etiological associations have also been suggested. Severe mood disorders can worsen oral health, and poor oral health could worsen mood disorder by increasing chronic low-grade inflammation. Mental health professionals should remain aware of the importance of oral hygiene in the clinical course of mood disorders and they should advise their patients to do regular dental checkups. [ Psychiatr Ann. 2024;54(8):e226–e229.]